Nonvolatile semiconductor memory device capable of uniformly inputting/outputting data
First Claim
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1. A nonvolatile semiconductor memory device comprising:
- a semiconductor substrate;
a plurality of memory blocks including a plurality of nonvolatile memory cells arranged in a matrix;
a plurality of word lines arranged in correspondence with a row direction of said plurality of memory cells;
a plurality of bit lines arranged in correspondence with a column direction of said plurality of memory cells; and
a control circuit for performing a writing operation on said plurality of memory cells at the time of a writing operation, wherein each of said plurality of memory cells includes;
first and second conductive regions formed in a main surface of said semiconductor substrate and connected to corresponding bit lines in said plurality of bit lines; and
an insulating film formed on said semiconductor substrate between said first and second conductive regions, having a first storing region in the vicinity of said first conductive region and a second storing region in the vicinity of said second conductive region, and said control circuit applies at least one pulse voltage to a selected memory cell in said plurality of memory cells, the memory device further comprising a counter for counting the number of times said control circuit has performed the writing operation since the memory device was shipped, wherein said control circuit varies the magnitude of a pulse voltage to be applied to a selected memory cell based on the number of times counted by said counter.
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Abstract
At the time of an operation of writing data to a specific memory cell in a memory block, a semiconductor memory device applies a write voltage for a predetermined period and, after that, performs a verifying operation by using a sense amplifier circuit and a comparator. When it is found as a result of the verifying operation that writing to the memory cell is insufficient, the writing operation is performed again by an instruction of a memory control circuit. At this time, the memory control circuit adjusts a write voltage.
47 Citations
10 Claims
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1. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate;
a plurality of memory blocks including a plurality of nonvolatile memory cells arranged in a matrix;
a plurality of word lines arranged in correspondence with a row direction of said plurality of memory cells;
a plurality of bit lines arranged in correspondence with a column direction of said plurality of memory cells; and
a control circuit for performing a writing operation on said plurality of memory cells at the time of a writing operation, wherein each of said plurality of memory cells includes;
first and second conductive regions formed in a main surface of said semiconductor substrate and connected to corresponding bit lines in said plurality of bit lines; and
an insulating film formed on said semiconductor substrate between said first and second conductive regions, having a first storing region in the vicinity of said first conductive region and a second storing region in the vicinity of said second conductive region, and said control circuit applies at least one pulse voltage to a selected memory cell in said plurality of memory cells, the memory device further comprising a counter for counting the number of times said control circuit has performed the writing operation since the memory device was shipped, wherein said control circuit varies the magnitude of a pulse voltage to be applied to a selected memory cell based on the number of times counted by said counter. - View Dependent Claims (2, 3, 4, 5)
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6. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate;
a plurality of memory blocks including a plurality of nonvolatile memory cells arranged in a matrix;
a plurality of word lines arranged in correspondence with a row direction of said plurality of memory cells;
a plurality of bit lines arranged in correspondence with a column direction of said plurality of memory cells; and
a control circuit for performing a writing operation on said plurality of memory cells at the time of a writing operation, wherein each of said plurality of memory cells includes;
first and second conductive regions formed in a main surface of said semiconductor substrate and connected to corresponding bit lines in said plurality of bit lines; and
an insulating film formed on said semiconductor substrate between said first and second conductive regions, having a first storing region in the vicinity of said first conductive region and a second storing region in the vicinity of said second conductive region, and said control circuit applies at least one pulse voltage to a selected memory cell in said plurality of memory cells, said nonvolatile semiconductor memory device further comprising a sense amplifier circuit for reading data stored in each of said plurality of memory cells, wherein said sense amplifier circuit is a single end type sense amplifier circuit.
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7. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate;
a plurality of memory blocks including a plurality of nonvolatile memory cells arranged in a matrix;
a plurality of word lines arranged in correspondence with a row direction of said plurality of memory cells;
a plurality of bit lines arranged in correspondence with a column direction of said plurality of memory cells; and
a control circuit for performing a writing operation on said plurality of memory cells at the time of a writing operation, wherein each of said plurality of memory cells includes;
first and second conductive regions formed in a main surface of said semiconductor substrate and connected to corresponding bit lines in said plurality of bit lines; and
an insulating film formed on said semiconductor substrate between said first and second conductive regions, having a first storing region in the vicinity of said first conductive region and a second storing region in the vicinity of said second conductive region, and said control circuit applies at least one pulse voltage to a selected memory cell in said plurality of memory cells, said nonvolatile semiconductor memory device further comprising a sense amplifier circuit for reading data stored in each of said plurality of memory cells, wherein said sense amplifier circuit includes a differential amplifier circuit which receives data of each of said plurality of memory cells and a reference potential. - View Dependent Claims (8)
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9. A nonvolatile semiconductor memory device comprising:
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a semiconductor substrate;
a plurality of memory blocks including a plurality of nonvolatile memory cells arranged in a matrix;
a plurality of word lines arranged in correspondence with a row direction of said plurality of memory cells;
a plurality of bit lines arranged in correspondence with a column direction of said plurality of memory cells; and
a control circuit for performing a writing operation on said plurality of memory cells at the time of a writing operation, wherein each of said plurality of memory cells includes;
first and second conductive regions formed in a main surface of said semiconductor substrate and connected to corresponding bit lines in said plurality of bit lines; and
an insulating film formed on said semiconductor substrate between said first and second conductive regions, having a first storing region in the vicinity of said first conductive region and a second storing region in the vicinity of said second conductive region, and said control circuit applies at least one pulse voltage to a selected memory cell in said plurality of memory cells, said nonvolatile semiconductor memory device further comprising a sense amplifier circuit for reading data stored in each of said plurality of memory cells, wherein said sense amplifier circuit includes;
a differential amplifier circuit which receives data of each of said plurality of memory cells and a reference potential; and
a reference potential generating circuit for generating said reference potential, said reference potential generating circuit including a plurality of reference cells operating at the time of a reading or writing operation, wherein said plurality of reference cells includes;
a read reference cell operating in a reading operation; and
a write reference cell operating in a writing operation and having a threshold value different from that of said read reference cell. - View Dependent Claims (10)
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Specification